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kevin5881

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Reply with quote  #11 
Thanks for the tips. It would be much easier to build the collector with inlet on one end and the outlet on the other. As for drilling the twin wall, I had planned on using aluminum angle to secure the twin wall, basically sandwiching it. I was going to install the fasteners on the top, bottom and sides of the collector using pole barn screws. This should provide a leak free collector and not cause any penetrating of the twin wall. I planned to leave a 3/8 gap between the panels and cover the gap with flat aluminum. Again the gap would allow the fastener to not penetrate the twin wall. Any idea how much an 8' sheet of twin wall expands when heated? Right now, my biggest problem is trying to figure out how to prevent overheating in the summer. That is my biggest concern. I cant think of a good way to cover it that will look good and not cost a fortune. Ventilating it seems like a waste of energy (the whole reason I am building this panel!) and if the fan were to fail, I don't know what the results would be.

stmbtwle

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Reply with quote  #12 
"In practical terms it is necessary to allow ~1/4” per 4’ length or width for thermal expansion."

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.archplastics.com/wp-content/uploads/polygal-technical-guide.pdf&ved=0ahUKEwip9bXo8OrVAhUFPCYKHc1bDUQQFgh0MAU&usg=AFQjCNE6B2sLEe3ZENpggf5ez_fhz-anjA

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
gbwillson

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Reply with quote  #13 
Kevin-

Head still spinning???

Expansion shouldn't be much of a problem as you shouldn't be allowing your collector to have output temps that high as it is wasting heat.  Acording to the Amerilux, the expansion is as follows:Thermal expansion of the sheet is approximately 3 mm per linear metre at a delta of 50°C(122F). And while the optimal output temps may be a few degrees lower than 122F, the glazing is still the coldest surface of your collector, so you should be safe if you use reasonable care when building. Panel expansion is greatest in the direction of the ribs. And seal the rib ends with either tape, silicone or screen tape. I've had water and spiders end up in the ribs, leaving watermarks and spider nests that can't be removed.

At the bottom of link below are the tech sheet and install instructions:
https://www.menards.com/main/building-materials/roofing-soffits-gutters/specialty-roofing/amerilux-4-x-8-clear-polycarbonate-twinwall-panel-6mm/p-1444424088575-c-5819.htm?tid=7672412174757968803&ipos=1

As for covering the collector during the summer months, you could look at using plastic panels as covers. Plastic bathroom wall panels could be secured in place to the cover the collector from the sun. White melamine panels are very cheap, although I would suggest painting the back and edges as any water that gets into contact with the masonite backing will cause swelling. I know someone used twinwall polycarbonate panels painted white. Should work very well as they are light, and virtually indestructable.

https://www.menards.com/main/paint/paneling-planking/paneling/dpi-trade-4-x-8-flat-smooth-white-melamine-wall-panel/p-1444428733772-c-8168.htm?tid=6731216516800473762&ipos=1

Having a way to prevent overheating should there be a stagnation event is always a wise idea. In the middle of winter, it wouldn't be much of an issue, but in the late fall and early spring the temps and sun angle are such that it can be real threat. Many ideas have been tossed around, such as battery backup, alarms, vent pipes. If you have ideas or want to brainstorm, post it. 

If your entry and exits are at opposite ends of the collector, the air flow WILL be even. Provided, of course, if the flow of air is PUSHED through the collector, and is a high enough volume. You only need a small amount of positive pressure in the intake manifold to make this happen. 

Greg in MN

stmbtwle

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Reply with quote  #14 
The plastic bathroom panels should work well. They're very thin, flexible, and lightweight, and would be easy to stow. They do yellow somewhat, but you could paint them.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
kevin5881

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Reply with quote  #15 
All great info so far, thanks. As of now, I am leaning toward trimming the panel with brick mold. This would give me a surface to fasten the sunshade to. Right now my my hiccup is that I will be deploying over the winter. My wife will be responsible for all home maintenance while I'm gone. I will need to come up with something simple or cover the panel for half of the winter while I'm away. Im kind of just thinking of a heavy canvas tarp screwed along the top and bottom edges. The bathroom panels also have me interested. Anyone have a link? I'm not sure I am thinking of the same panels. I may also have access to a free concrete blanket. It is basically a heavy tarp that is reflective on one side. Ill have to see how big and how heavy it is.
gbwillson

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Reply with quote  #16 
Willie makes a good point. Plastic bathroom panels yellow aren't likely to be UV rated and would therefore become very brittle and fail in short order. So painting would be a good idea. I have several 4'x15' heavy canvas drop cloths that you could add some grommet holes for hanging and securing the edges. You might find an awning or tent manufacturer that sells remnants. Might be easier than climbing having the misses climbing a ladder with a large panel. 

Krautman's wife made his cover out of the roofing material from the old Metrodome in Minneapolis when they tore it down. She sewed it so it would wrap around the unit and added reinforced grommets around the edges so it could secured with rope.
2454521.jpeg 

Greg in MN





stmbtwle

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Reply with quote  #17 
How about the tarp fastened at the top only, and maybe to a length of PVC pipe at the bottom. Roll it up when not needed, secure in place with bungees when in use. You can get white plastic tarps online pretty reasonably.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #18 

The plastic bathroom panels should work well. They're very thin, flexible, and lightweight, and would be easy to stow. They do yellow somewhat, but you could paint them.

Fiberglass Reinforced Plastic (FRP) also known as Glass Reinforced Plastic (GRP)?
They tend to have UV stabilizers to prevent cracking and fading from sunlight through the windows. 

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Rick H Parker
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Electronics Engineering Technologist
gbwillson

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Reply with quote  #19 
Rick-

Good to know about the UV protection in the FRP panels. There was no mention of it on the labels.

Greg in MN
kevin5881

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Posts: 11
Reply with quote  #20 
Great suggestions! Now I am thinking of the white roofing material. I cant remember what it is called but it is the stuff that is replacing the black epdm roofing. I could secure it at the top and roll it down using a couple of sticks of conduit.
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